1. Field of the Invention
The present invention relates to an electrically conductive socket, and more particularly to a zero insertion force socket used for engaging with terminals of a CPU of a personal computer, in which the contacts of the socket more reliably contact with the terminals.
2. Brief Description of the Prior Art
Various kinds of zero insertion force sockets have been developed, whereby terminals of a CPU of a personal computer can be inserted into and withdrawn from such sockets without insertion and withdrawal force. This facilitates necessary change or replacement of the CPU.
A widely used conventional zero insertion force socket substantially includes a socket housing having a plurality of insertion holes formed therein and a plurality of metal-made conductive contacts respectively disposed in the insertion holes. The insertion holes of the socket are receptive of multiple terminals of an integrated circuit. According to the zero insertion force arrangement, during the insertion and withdrawal of the integrated circuit in the socket, the integrated circuit will not suffer any resistant force of the contacts of the socket. After the terminals are inserted into the insertion holes, an operation lever is moved to push a movable plate disposed over the socket housing to slide through a small distance (usually 1 mm) relative to the socket housing, whereby the terminals are urged to move toward the contacts and squeeze into a space between two opposite conductive elastic plates of the contacts. Several shortcomings exist in such structure as follows:
1. Because the elastic force of the two opposite elastic plates of the contacts is hardly completely identical, it often takes place that one of the elastic plates has greater elastic force and pushes the other elastic plate away a middle position, that is, the two elastic plates cannot be located at their true positions. As a result, the terminals of the integrated circuit often cannot be smoothly forced into the space between the two elastic plates. PA1 2. The error of manufacturing often causes that a center of the clearance between the two elastic plates is not aligned with a center of the insertion hole. This will result in that the terminals can be hardly smoothly squeezed into the space between the the elastic plates. PA1 3. Each contact has two elastic plates so that it will consume two pitches (one pitch equals 2.54 mm and two equal 5.08 mm) of material to manufacture each contact. PA1 4. After formed by punching, the pitch of the contact is 5.08 mm, so that when a row of contacts are together inserted into the insertion holes of the socket housing, the pitch of which is 2.54 mm, the installation procedure is only half completed, that is, one contact is inserted into one of each two insertion holes and the other of each two insertion holes is free from the contact. Therefore, the installation procedure must be performed one more time to complete the insertion operation of a complete row of contacts into the insertion holes. Therefore, the installation procedure must be performed twice. This is troublesome and will reduce the efficiency of the automatized production procedure. PA1 5. In the case that the pitch of the punched contact is less than 5.08 mm while more than 2.54 mm, because such pitch is not equal to the standard 2.54 mm pitch, when installing the contacts into the insertion holes of the socket housing, only one contact can be inserted into one of the insertion hole each time. Accordingly, the installation efficiency will be very low.
It is therefore necessary to provide an improved zero insertion force socket to eliminate the above shortcomings. Such socket has improved contacts and insertion holes which can accurately locate the elastic engaging portions of the respective contacts at their true positions so that the terminals of the integrated circuit can be easily and smoothly inserted into the insertions holes of the socket.